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Pyrocat HD Purchased from the Formulary.  I considered purchasing the raw chemicals but there is uncertainty with storing bulk chemicals, (especially the potassium carbonate), and quality control.  The kits are adequate and inexpensive enough for my purposes.  I would need to double my volume first.   Anyone wishing to use the Pyrocat is advised to read the article at the link below, written by the inventor, Sandy King, before proceeding.


Stock Solution A

Distilled Water

   750 ml

Sodium Bisulfite

   10  g


   50 g


     2 g

Potassium Bromide

   2  g

Water to make

   1000  ml

Stock Solution B

Distilled Water

   1000  ml

Potassium Carbonate

   1000  g

To make a standard working solution mix 1 part A with 1 part B
with 100 parts water.

* Or substitute 25 grams of Metol (with a slight loss in film speed).

The mixing of solution A was straight forward, I used distilled water.  It is recommended to mix the phenidone with a bit isopropyl alcohol, although I had no trouble with the small kit.  The larger kit will have more to dissolve.  Anyway I use a magnetic stirring heating plate so my hands don't get tired.  Wear gloves and watch the ventilation, the Pyro is nasty stuff get it dissolved ASAP. 

Solution B, potassium carbonate, was the most difficult to mix, it is almost a super saturated solution, so mixing needs to take time, small amounts and a lot of stirring.  It took almost 20 minutes to get it all in, then another 10 to get it all dissolved.  Be cautioned that the final solution will increase about 10-15 percent.  There is also an exothermal reaction

Sandy King wrote:
I will also recommend my own Pyrocat-HD formula, a staining developer based on Pyrocatechin/Phenidone. It is less expensive to mix than PMK and ABC+ and works in place of either of them: a 1:1:100 dilution of Pyrocat works almost exactly like PMK 1:2:100 (both in terms of development times and curve characteristics), while diluted 2:4:100 it replaces ABC+ (and is even superior to it for zonal expansion of tough films like BPF and HP5+). Pyrocat also is much less likely to stain film than pyrogallol based developers like PMK and ABC+ which must be used with rotary processing with great care.

Normal Agitation Normal agitation for tank development is considered to be continuous agitation for the first 60 seconds of development, then agitation for 5-10 seconds every 30-60 seconds thereafter.  With this pattern of agitation Pyrocat-HD can be used with no modification to your normal development procedures for conventional developers.


Minimal Agitation Minimal agitation consists of continuous agitation for the first 60 seconds of development, followed by 10 seconds of agitation every third minute. With this method a pre-soak of five minutes is strongly recommended to avoid the possible formation of bubbles on the emulsion. Minimal agitation has three desirable results: 1) it gives great apparent sharpness through the formation of maximum adjacency effects,  2) it provides a compensating effect, and 3) it provides increased emulsion speed.

With minimal agitation you should extend development time about 50% over the normal time required for intermittent agitation, but experiment before risking valuable negatives.


EFKE KB-25R Development Stats:  Single reel stainless steel tank, inversion and twist agitation.


1.  Pre Soak 1 minute

2.  Pyrocat 2:2:100.

3.  Stop with water,  four dumps.

4.  Fix 5 with Alkali based fixer.  Medium agitation first 60 sec then for 5 seconds every subsequent 15 seconds.

5.  Wash 15 minutes

6.  Photo flow 30 sec

7.  Hang dry


Densitometry - Measurements can not be taken with the Macbeth TD-502 because of the staining effects, a blue channel needs to be used.



Best development times for KB25R ASA 25 as per visual inspection and subsequent scanning:




Time (min) Normal Agitation

Time (min) Minimal Agitation

N-1 8.5 12
N 10 16
N+1 12 20

Non Technical Impressions about Pyrocat HD

My impression after about 10 rolls of 35mm and 6x9cm is one of glee.  I am very impressed with the performance to price return.  Grain is gorgeous, tone development is gorgeous, and the staining action compensates so well that exposure is almost an afterthought.  Negatives which looked way too dense or thin showed balanced highlight and shadow detail which surprised the heck out of me.  I never felt the negative was lacking even when the exposure was off  a stop or two.  The Pyrocat was easier to control in the tank then other developers I've worked with.  Reduction or increase in development times followed standard logic which tells me that agitation is less important for contrast development then just time.  The result is an easy to use developer where acutance is controlled with agitation and contrast is controlled with time.  Suffice it to say I ordered another, larger, kit from the Formulary.